Automatic stoker



W. A. HARE AUTOMAT I C STOKER Filed July 14, 1919 Patented Nov. 4, 19240 PATENT OFFICE.

wrnrnnn A. HARE, or DETROIT, MICHIGAN.

AUTOMATIC STOKER.

Application filed July 14, 1919. Serial No. 310,794.

To all whom it may concern."

Be it known that I, WILFRED A. HARE, a subject of the King of England, residing at Detroit, in the county of Wayne and State of Michigan, have invented certain new and useful Improvements in Automatic Stokers, of which the following is a specification, reference being had therein to the accompanying drawings.

In forced draft furnaces where the air for maintaining combustion is forced upwardly between the grate bars, it is common practice to provide an air tight chamber beneath the bars into which the air is introduced in various ways, preferably through hollow grate bars to cool the bars and to heat the air. To provide a'furnace with such a chamber complicates the structure and its installation, and leakage causes inefiicient operation.

Further, the air under pressure in such a chamber will travel in paths of least resistance and therefore it is diflicult to maintain an even distribution of air over the entire grate surface. The present invention contemplates the overcoming of these difficulties by confining theair within a plurality of? passages directly below the grate surface upon which the fuel is burned, and delivering it directly from these'several passages to the several spaces between the hollow bars providing such surface, thus securing an even distribution of air to the grate surface and obviating the necessity for installing and maintaining an air-tight chamber beneath the grate comprising the several hollow gratebars. A further object of the invention is to provide a suitable ash grate which will catch all unburned fuel and to which air is supplied for burning such fuel, said grate being arranged to facilitate the removal of ash and clinkers, and further, to provide certain other new and useful features in the construction, arrangement and combination of furnace parts, all as hereinafter more fully described and shown in the accompanying drawing.

With these and other endsin view,'the invention consists in the matters hereinafter set forth, and shown in the drawing in which Figure 1 is a vertical section through a portionof a furnace iilustrative of the in-.

vention, and showing one side of a hollow grate bar partly broken away and in sectIOII as shown at the lower side of Fig. 3; Fig. 2 is a similar view illustrating the movements of the grate bars;

Fig. 3 a plan view of several grate bars Wltlf portions broken away and in section to show the construction; and

Fig. 4 is a cross-section of a plurality of grate bars substantially upon the line IV-IV of Fig. 3.

To illustrate an application of the invention to a furnace, the same is shown as appl ed to an automatic stoker having a retort 1 into which the fuel is fed in the usual manner (not shown), and wind box 2 beneath the retort for supplying air under pressure tomaintain combustion. Supported upon the upper edges of the wind box and retort and spanning the space between sald edges at one or both sides of the retort, is a suitably constructed hollow twyer or twyers 3, and extending laterally from one or both sides of the wind box are hollow grate bars at and 5 forming the grate upon which the fuel is burned withthe upper ends of said bars supported upon the wind box and in communication with said box through the twyer. A suitable channel beam 6 forms a support for the lower ends of the grate bars and spaced from said lower ends is a furnace side wall 7, the space between said.

wall and grate being closed by an ash grate 8 which rests at one end within a clean-out opening .9 in said wall closed by a suitable door or doors 10, the inner end of said ash grate being pivotally attached at 11 to the ends of the movable grate bars 5, to move therewith.

The fixed (4c) and movable (5) grate bars are arranged in alternate relation to make up the grate upon which the fuel is burned, and these movable bars are each provided withthe usual socket 12 at its lower end to receive a supporting rib 13 on a rock shaft 14 which is mounted in bearings 15 on the beam 6. ihis shaft is rocked in any suitable manner, as'by an arm 16 on the shaft and an operating rod 17 connected to the lower end of the arm and receiving motion from other .rnoving parts (not shown) of the mechanism. Upon rocking the shaft M, the grate bars 5 are raised slightly at their lower ends and moved endwise in the usual manner to agitate the fuel and feed it down upon the grate toward the ash grate 8 which receives the ash and clinker, and in turn ischarges the same into the clean-out opening 9. The pivotal connection of the ash grate to the grate bars permits of the free rising and falling movement thereof and as the outer end of the ash grate rests by gravity upon the bottom wall of the opening 9, free longitudinal movement is ermitted, said end of said ash grate sli 'ng freely within the opening to feed ash and clinker into it. These products of combustion may therefore be readily cleaned out at any time by opening the door 10 and without interfering with the continuous operation of the furnace, and the entire grate surface and, operation of the furnace may be observed, by opening said door.

The lower ends of the fixed grate bars are supportedin the usual manner by a suitable rib 18 carried by the beam 6 to engage a notch in the lower side of each bar, and at their upper ends, all. of the grate bars are supported upon'a shelf or ledge 19 projecting laterally from the side of the Wind:

box 2.

, Each grate bar is formed with a plurality of longitudinal'air passages, there being two air inlet passages 20 directly below the upper surface of each bar upon which the fuel 'is'bu'rned, and these passages open through the upper end of the .bar directly into the hollow twyer 3 to receive air passing upward therethrough from the wind box. Near the lower ends of the bars, an opening 21 is provided in the bottom of each passage 20, through which openings the air passes into channels 22 directly below the passages 20. These return or outlet channels 22 are formed inadjaoent sides of ad-' jacent bars, that is, the channel in one side of one bar confronts the channel in the adjacent side of the next bar and these con fronting channels together form a return or outlet duct in adjacent bars, so thatthe slots or openings 23 in the grate surface between adjacent bars,'are in direct communication with these channels 22 which. together form the outlet or return ducts,- the air in said ducts being'free to pass upwardly and out through the several slots between thebars throughout their length tb maintain combustion upon the grate. The lower side edges of the several bars are formed to fit tightly together, they being flanged downwardly as at 2st to provide edge contact faces which will prevent the escapeof air between said edges from the return ducts formed by the channels 22. The upper or twyer ends of the several return ducts are closed by an end wall 25 but in the movable bars 5, slots or openings 26 are provided in the bottom wall 27 of each c annel 22 act jacent saidend wall 25 to permit the escape I shelf 19 upon which said ends of the bars rest and slide. When these movablegrate bars are moved longitudinally to the opposite end of their stroke 'as shown in Fig. 2, these openings 26 will be opened and permit air to escape into the space 28 below the grate, and as this space is in free communication with the spaceor chamber 29 below the ash grate 8, the air escaping intermittently through the openings 26 from the return ducts formed by the channels 22, will maintain combustion upon theash grate of any guel which has not been burned in passing own the grate bars;

To facilitate manufacture and to provide grate bars which are constructed for strength and lightness in weight, a particular construction 'is shown in the drawings, but it'- will be understood that any suitable form of grate bars having longitudinal channels forming return ducts may be em.- ployed. v i 'As particularly shown in Fig. 4, each grate bar comprises a central vertical longitudinal web 30 extending from the upper wall of the bar to the lower wall 27 thereof. This web gives rigidity to the bar to prevent sagging under load and extreme heat and the longitudinal passages 20 are formed by providing side plates 31 which are secured in any suitable manner to the bar to 'form the passages 20 between them and the central web, said plates being flanged inwardly at their lower edges to meet ribs 32 extending laterally from the sides of the web 30 at a distance above the lower wall 27 of the bar. These flanges 32 together with the plates 31 form the dividing wall between the passages 20 and channels 22 and as the passages 20 are directly below the upper wall which forms the fuel surface of the grate, the cold air passing into the upper open ends of these passages from the wind box 2, efiectively cools the grate surface and prevents the grates from burning out. The streams of air lllti sides ofthe bars. *These ducks are in direct communication throughout their lengths with the slots 23 between the several bars so that this heated air is efiectively distributed by the several ducts over the entire grate and escapes through the slots 23, maintaining combustion upon the grate.

The entire volume of air for maintaining combustion is thus divided into a large number of streams, one for each slot 23, and thus the air is directed and forced to all parts of the grate evenly. The openings 26, which are intermittently opened by the movement of the movable grate bars, supply just sufficient air to the chamber 29 beneath the ash rate, to maintain combustion upon the ash grate of any residue of fuel which may be carried down with the ash and clinker and discharged upon said grate. The reciprocating movement of the movable grate bars imparts a similar movement to the ash grate to cause the ash and clinker to be finally discharged over the end of the ashgrate into the clean-out chamber 9 located in the side wall of the furnace where it may be readily removed without interrupting the operation of the furnace. The uper ends of all of the grate bars project into the hollow twyer 3 and as this twyer spans the space between the side of the wind box and the adjacent side of the retort, the air has a free flow into the open lower end of the twyer where it divides, part passing through the twyer openings 33 and the remainder passing directly into the open ends of the grate bars, through the unobstructed passages 20, and return air ducts formed by the channels 22 from which it flows freely and is thereby confined and directed to the slots between the several bars. The lower wall 27 of each bar being flanged and faced off along its edges to engage the edges of the lower walls of the adjacent bars, makes a tight joint between the lower walls of the severalv bars and closed air ducts, each comprising two confronting channels 22 are thus formed between the bars, and the escape of air'through the joints into the space or chamber 28 below the grate bars is prevented;

Obviously the structure of the several grate bars may be changed to suit the conditions to which they may be put in use and. they may be formed with one or more longitudinal passages 20 and with one or more of the channels 22 communicating therewith and with the discharge slots, between the bars. It is also obvious that the volume of air passing out of the hollow grate bars may be divided and directed by anysuitable means to the several slots between the grate bars for maintaining combustion without the necessity for maintaining an air tight chamber beneath the grate and I do not, therefore, limit myself to the particular construction of grate barsshown in the drawings. The invention may be applied toother forms or construction of furnaces in which stationary or movable or part stationary and part movable grate bars are used and theparticular arrangement of stationary and movable grate bars and mechanism for operating the same may also be varied without departing from the spirit ofthe invention: I do not there-' fore limit myself to the form or arrangement of furnace shown in the drawing which is illustrative of an application of my invention. i

What I claim is:

1. In a furnace the combination of a plurality of grate bars each formed with a longitudinal passage adjacent the upper surface of the bar and open at one end of the bar to receive air under pressure, and also formed with a longitudinal channel below said passage, said channel being in .communication with said passage at the end of the bar opposite its openend, said channel being open through a side of the bar substantially throughout its length to discharge the air laterally into the space between adjafent bars, said bars being formed to close the space between adjacent bars at the lower side of the grate.

2. In a furnace, a grate having a plurality of passages extending longitudinally thereof adjacent the upper surface of the grate and open at one end of the grate to receive air, said grate being also formed with air ducts extending longitudinally of the grate beneath said passages and in communication with said passages adjacent the end of the grate opposite that through which the passages open,.said air ducts each opening through the surface of the grate between said first named passages and substantially throughout the length of the grate.

3. In a furnace the combination of a plurality of grate bars arranged side by side I and in contact at the lower side of the grate to form an impervious wall at the lower side of the grate, said bars being also formed to provide longitudinal slots in the upper grate surface between the bars and each bar being formed with a longitudinal passage opening'through one end of the bar to receive air, and also formed with a longitudinal channel beneath said passage, which channel is in communication with said passage and opens into the space between adj acent bars to discharge air through, the slots in the grate surface.

4. In a furnace, the combination of a phi-- rality of grate bars formed to contact each other adjacent the lower side of the grate and form an impervious lower wall for the grate, said bars being also formed to vprovide longitudinal slots in the upper grate surface between the bars a plurality of longitudinally extending air passages and air duets, said passages for conducting air throughout the length of the grate adjacent the upper surface thereof to cool said surface, and said ducts arranged to receive air from said passages and discharge the same upwardly through said slots in the upper grate surface.

5. In a furnace, a grate comprising a plurality of hollow grate bars formed to closely contact each other at'the lower side of the grate and together form an impervious bottom wall for the grate, said bars being also formed to provide longitudinal slots in the upper grate surface between adjacent bar's, said hollow bars each being open at one end to receive air under pressure and formed to conduct the air to the opposite end of the bar, adjacent bars being formed to receive the air at the ends of the bars to which it is conducted and discharge the same into and upwardly through the slots in the upper grate surface.

6. In a furnace, a grate comprising a plurality of grate bars each having an air inlet passage open adjacent one end of the bar to. receive air under pressure and having a channel beneath said air inlet passage, said channel communicating with the said passageat the end of the'bar opposite that through which the passage opens, said channel opening through aside of the bar and forming together with a channel in an adjacent bar, a passage which ,is open upwardly through the grate surface between adjacent bars.

7. In a furnace, a grate comprising a plu-.

rality of fixed and movable hollow grate bars adapted to receive air and to discharge the same throughout the grate surface, said movable bars having openings adapted to be opened intermittently bythe movement of said bars to discharge air therefrom for maintaining combustion other than upon said grate surface.

8. In a furnace, a grate comprising a plurality of fixed and movable hollow grate bars adapted to receive air under pressure and to discharge the same directly through the grate surface for maintaining combustion thereon, said movable grate bars being provided with outlet openings adapted to be opened and closed by the movement of said bars.

9. In a furnace, a grate comprising a plurality of fixed grate bars and movable grate.

bars, all of said bars being formed with inlet passages to-be supplied with air under pressure, said bars being also formed to provide outlet ducts communicating with said inlet passages, said outlet ducts being arranged to discharge directly through the grate surface substantially throughout the length of the grate, and each of said movable bars being provided with an outlet opening for one of said outlet ducts, said outlet openings being arranged to be opened and closed by the movements of said movable bars. 7

10. In a furnace, the combination with a twyer, and means for supplying air under pressure to said twyer, of a grate formed of a plurality of grate bars each having a plurality of separate longitudinal air passages open at one end into said twyer, and also formed with a plurality of separate longitudin'al channels below said passages openmg through the sides of the bar and communicating with said passages at-the end forming longitudinal alr passages opening through the upper grate surface between the bars, said bars being in close contact at their of the bar opposite the open end of the passages, the channels in adjacent bars together lower sides to provide an impervious lower supports and together forming a grate, each bar being formed with a longitudinal air inlet'passage opening through one end of the bar,into the twyer, and with a return air outlet channel beneath the inlet passagecommunicating with the inlet passage at the opposite end of the bar, said return channel opening into the space between adjacent bars, said bars being in contact with each other adjacent the lower sides thereof to prevent the escape of air through the space between thebars into "the space below the grate.

12.'In afurnace, the combination with 'a hollow twyer and means for supplying air under pressure to said twyer, of a plurality of fixed and movable inclined grate bars each formed with a longitudinal passage opening through the upper end of the bar into thetwyer and with a longitudinal outlet channel adjacent the lower side of the bar communicating with the inlet passage adjacent the lower end of the bar, the outlet channel being open through a side of the bar into the space between adjacent bars to discharge upwardly therethrough throughout the length thereof between adj acent bars, said ad acent bars being in contact at their-lower edges toprevent the escape of air from the outlet passage into the space below the grate.

13. In a furnace, the combination of a hollow twyer, means for supplying air under pressure to the twyer, a plurality of hollow inclined grate bars supported with their open ends in communication with the twyer, means adjacent the lower ends of said bars for moving certain of said bars longitudinally, a support for the upper ends of the movable bars upon which they are free thereon, from the discharge openings in the i grate bars.

14. In a furnace, the combination of a wind box, a retort supported upon the wind box, a hollow twyer spanning the space be serene? tween the side of the retort and the side of the wind box, a plurality of inclined hollow grate bars supported at their upper ends by the Wind loox with said ends in open communication With the twye'r, a support for the lower ends of said bars, means for moving certain of said bars, a wall adjacent the lower ends of the bars and spaced therefrom, a clean out opening in said.v wall and.

a grate connected at one end to the movable 1 bars and supported at its opposite end Within said clean-out opening.

In testimony whereof I aifix my signature in the presence of two Witnesses.

v WILFRED A. HARE. Witnesses:

ANNA M. Dorm, LnWIs E. Fnerm 

